1. Field of the Invention
This invention relates to a method by which an air handling duct system may be designed and constructed so as to be substantially fully "pre-balanced" and thus eliminate or substantially reduce the necessity for a technician to test and make modifications to the duct system after construction thereof in order to obtain substantially the correct air flow discharges at the various air outlets thereof.
2. Description of Related Art
Various different forms air handling duct systems heretofore have been provided and angular turns in air handling systems have been equipped with turning vanes to reduce resistance to air flow at angular turns of the duct system. In addition, downstream legs of air supply duct systems are conventionally provided with extractors and adjustable dampers, after construction of air handling duct systems, in order to obtain proper "balance" of the duct system so that the various air outlets thereof will discharge the designed air flow volumes. Of course, the addition of extractors and/or dampers increases the overall resistance to the flow of air through the duct system and, accordingly, the operational speed of the associated fan must be increased or the fan must be replaced with a more powerful motor or motor and fan assembly of a larger capacity, all of which modifications made to a pre-designed air handling duct system in order to balance the same result in considerable expense.
In addition, if it does become necessary to replace a pre-determined fan with a more powerful larger capacity fan or motor due the necessity of adding extractors and dampers to the designed air handling system, further balancing of the system may be required after the upgrade of the motor or motor and fan assembly thereof, inasmuch as the upgraded assembly may have different performance curves as to static pressure and volumetric discharge. This further increases the cost of "balancing" an air delivery duct system to fall within the usual plus or minus 5 or 10 percent (as required by the system design) of the designed air volume discharge at each of the outlets of the duct system.